On Thu, 2007-07-26 at 11:48 -0700, Andrew Morton wrote: > On Thu, 26 Jul 2007 13:40:19 -0400 Neil Horman <[email protected]> wrote: > > > Currently, core dumps can be redirected to a pipe by placing the > > following string template in /proc/sys/kernel/core_pattern: > > |<path/to/application> > > This patch extends this ability, allowing the core_pattern to contain arguments > > to be passed as an argv array to the userspace helper application. It also add > > a format specifier, %c, which allows the RLIM_CORE value of the crashing > > application to be passed on the command line, since RLIMIT_CORE is reduced to > > zero when execing the userspace helper > > This all seems to be getting a bit nutty. Who needs this feature > and what will they do with it, etc? We're using it for doing a system-wide crash dump handler. Currently Ubuntu's using it with their Apport tool[1] for this purpose; I'm adapting that for Fedora. The Ubuntu approach requires a kernel patch that adds a bunch of process information (process pid, RLIMIT_CORE, etc) to the environment of the crash handler[2]. Most of that information can instead be parsed out of the ELF headers - which is what I wrote code to do[3]. The problem that remains is determining the value of RLIMIT_CORE. (This is used to determine whether the user wants a normal corefile, thus retaining normal core dump behavior). As I understand it, getrlimit() won't return the correct values while dumping to a pipe. So we need to pass the original RLIMIT_CORE to the userspace helper somehow. It seems sensible to pass arguments to a userspace program by using argv[]. So there we are. There's probably many other uses for this stuff but that's the specific one we're targeting. Does that make sense? If there's an easier way to get the original RLIMIT_CORE from inside the crash handler, I'd love to hear it. -w [1] https://wiki.ubuntu.com/Apport [2] http://kernel.ubuntu.com/git?p=ubuntu/ubuntu-feisty.git;a=blob;hb=HEAD;f=fs/exec.c#l1557 [3] http://rdr.to/bX
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